Because of a growing appreciation for the benefits of regular exercise; and because constraints of time and space prevent many persons from indulging in activities such as running, swimming and walking, the market for exercise equipment is rapidly increasing. It is generally desirable to exercise a number of different muscles over a fairly large range of motion so as to provide for even physical development and a maximum level of aerobic exercise. It is further desirable that exercise equipment provide a smooth, relatively natural motion so as to avoid jarring or irregular strains which can damage muscles and joints. It is also desirable that exercise equipment be relatively easy to use and of simple, low cost construction.
While a number of different exercise systems are known in the prior art, such systems suffer from a number of shortcomings which limit their utility. Stationary bicycles are widely used; however, they are employed in a sitting position and consequently, the number of muscles exercised is small. Furthermore, the range of motion provided by a stationary bicycle is fairly limited. Stationary devices for simulating cross country skiing are also in widespread use. While these systems exercise more muscles than do stationary bicycles, the relatively flat, shuffling foot motion provided thereby does not adequately exercise all of the leg muscles through a wide range of motion. Stair climbing equipment also exercises more muscles than do stationary bicycles; however, the rather limited up and down motion provided thereby does not exercise leg muscles through a large range of motion. Treadmills and the like permit walking or jogging in a relatively limited area; however, they can be quite jarring to knee and ankle joints, and many users find it difficult to maintain balance on a treadmill.
U.S. Pat. No. 4,720,093 shows a climbing type exerciser. Pat. No. 4,509,742 shows a stationary bicycle which provides for arm motion. Pat. No. 2,603,486 shows a bicycle type exerciser providing for combined arm and leg motions. Pat. No. 5,039,088 shows another bicycle type exerciser providing for hand motion.
U.S. Pat. No. 3,316,898 discloses a rehabilitation device for passive use by a seated person. The device includes a motor which raises and lowers a set of foot supporting plates so as to flex the ankle, knee and hip joints. A similar device is shown in U.S. Pat. No. 4,185,622. German Laid Open Publication 29 19 494 discloses an exercise device in which a set of foot supporting plates are disposed so as to undergo a combination of sliding and rotary motion to provide a stepping action. It has been found that while these apparatus produce a stepping motion, the motion does not simulate natural running and walking.
In response to the shortcomings of the prior art, the inventor of the present invention has previously developed a stationary exercise device which is disclosed in U.S. Pat. Nos. 5,242,343; 5,383,829; 5,518,473 and 5,562,574. The apparatus of the foregoing patents provides a natural running and stepping motion in which the user's heel initially rises at a faster rate than the toe, on a forward step, and in which the heel initially falls at a faster rate than the toe on a backward step. The present invention is directed to an exercise device which is configured differently from those in Pat. Nos. 5,242,343; 5,383,829; 5,518,473 and 5,562,574, but which achieves a similar, beneficial foot action.
The apparatus of the present invention is simple to manufacture and use, compact in design, and provides a smooth, natural action which exercises a relatively large number of muscles through a large range of motion. These and other advantages of the present invention will be readily apparent from the drawings, discussion and description which follow.